The present disclosure relates to a circuit board. More particularly, the present disclosure relates to the field of improving the accuracy of detecting whether a solder joint of a connection terminal to a land is successful or not, by providing a narrow portion which is narrower than other portions. The land is used to join a distal end portion of the connection terminal of a lead component by soldering.
A variety of kinds of electronic devices such as a television receiver, personal computer, and audio equipment include a circuit board disposed therein. The circuit board may include a wiring plate on which a circuit pattern is formed on an insulation substrate using a copper foil and a plurality of electronic parts mounted on the circuit pattern of the wiring plate.
In such a circuit board, a lead component such as a QFP (Quad Flat Package) or a connector may be used as electronic parts. The lead component includes a main body formed of ceramic and other material, and a plurality of connection terminals protruding from each side of the main body. Each of the connection terminals is joined to each corresponding land of the circuit pattern by soldering (for example, see FIG. 6 in Japanese Patent Application Laid-Open Publication No. 2003-10216).
The lead component is a component in which the quality of electronic devices in the market is greatly affected by thermal deformation behavior and the quality in the initial stage. The lead component is necessary to ensure the high quality of circuit board in a mounting process.
Therefore, in the mounting process of the lead component, after the lead component is mounted such that each of the connection terminals is joined to each corresponding land by reflow soldering, an inspection device inspects whether a solder joint of the connection terminal to the land is successful or not.
The inspection of whether the solder joint is successful or not is performed by two- or three-dimensional image detection or the like.
In a two-dimensional inspection, for example, light is irradiated on a soldered portion at a distal end side of the connection terminal from among the solders (solder fillets) applied to the lands, and the light is irradiated in a direction perpendicular or oblique to the soldered portion. Then, the determination of whether the solder joint is successful or not is made based on the difference in the shape or luminance level of the portion irradiated with light.
In addition, in a three-dimensional inspection, for example, a float amount indicating how far away the connection terminal is from the land is detected, and then the determination of whether the solder joint is successful or not is made based on the float amount of the connection terminal with respect to the land.